Liquid level indicating system for use in treating wells



UMUIUIR UVM J A All"l 25, 1944- K o. E. BARsTow 2,347,589 LIQUID LEVELINDICATING SYSTEM FOR USE INl TREATING WELLS Filed Sept. 2, 1941 2sheets-.sheet 1 i EK?" "4 *L w i I 1` A TREAT/NG ma/.a E f FEED/NGDEV/CE Y AND /N72PFC j LOCATOR 'C'WD 1g FOR C'U/VTAC'//VG 3 INVENTOR.Ormond banslow BY mgl TTLK/ YJ 'n VAK r W* Y' e auf t fff'hv April 25,1944. Q E, BARS-row 2,347,589

LIQUID LEVEL INDIGATING- SYSTEM FOR USE IN TREATING WELLS Filed Sept. 2,1941 2 SheetS--Sheet 2 I N V EN TOR. r'monq/ f. ar'f/ow TTOLU YJ SearchRooI UNITED STATES PATENT OFFICE LIQUID LEVEL INDICATING SYSTEM FOR USEIN TREATING WELLS Ormond E. Barstow, Midland, Mich., assigner to The DowChemical Company, Midland, Mich., a corporation of Michigan ApplicationSeptember 2, 1941, Serial No. 409,200

(Cl. 7f3-51) 6 Claims.

The invention relates to a method and apparatus useful in connectionwith the treatment of an earth or rock formation penetrated by `a wellbore with an electrically conductive liquid. It more particularlyconcerns an apparatus whereby the level to which an acid solution risesin the well bore can be accurately ascertained at all times during anacid treatment of an earth or rock formation penetrated by the bore of awell.

In introducing liquid agents into an earth or rock formation, such asfor example, when introducing an acid solution into the porouscalcareous formation penetrated by the bore of an oil well, it is theconventional practice to attempt to control the level to which the acidrises during its introduction by maintaining the acid solution under acolumn of oil or the like as it is forced into the formation. However,it oftentimes happens that the formation adjacent a portion of the oilcolumn is highly porous allowing the oil to escape into the formation,with the result that the acid rises in the well bore and escapes into asection of the formation which may be of an unproductive nature oralready highly porous. Waste of the treating solution thus occurs. Inaddition, it sometimes happens when carrying out such a treatment thatthe acid may rise in the'well bore during treatment to a point where itattacks and disintegrates the cement around the casing necessitatinganother cementing operation before the well can be satisfactorilyproduced.

It is, therefore, the principal object of the invention to provide anapparatus which may be suitably used in connection with treating a wellwith an electrically conductive liquid whereby the level to which saidliquid rises in a well bore during its introduction into the earth androck formation surrounding the well bore can be ascertained at all timesduring the treatment.

Still other objects and advantages of the invention will be apparentduring the course of the following description.

The invention, then, consists in the apparatus hereinafter more fullydescribed and particularly pointed out in the claims, the accompanyingdrawings and following description setting forth in detail one mode ofcarrying out the invention, such mode illustrating, however, but one ofvarious ways of carrying out the invention.

In the drawings:

Fig. l is a diagrammatic view partly in section of an oil well equippedfor carrying out a treatment according to the method of the invention.

Figure 2 is a detailed view in cross section of CTI the lower portion ofthe level measuring device shown in Figure 1.

Figure 3 is a diagrammatic view similar to that of Figure 1 showing,however, a slightly modified apparatus arranged for carrying out atreatment according to the method of the invention.

Figure 4 is a detailed view of the lower portion of the measuring deviceshown in Figure 3.

As shown, the upper portion I of the well bore is cased with a metalpipe 2, while the lower portion 3 of the Well bore is uncased and endsin productive stratum 4. Extending from the well tubing string 5 withits lower end adjacent the productive stratum 4, the uid level measuringdevice 6 is shown in position for carrying out a treatment in accordancewith the method of the invention. The lower portion of the well bore isshown lled with acid solution 'I up to a point 8 adjacent the upperlevel of the productive stratum. The remainder of the well is shownfilled with a pressuring fluid 9, such as oil. Above the ground level,pipe IIJ, controlled by valve I I, communicates with the interior of thewell through casing head I2, while pipe I3, controlled by valve I4,communicates with the well through tubing string 5. Extending throughpacking gland I5, attached to the-upper end of tubing string 5,insulated conducting cable I6 passes over sheave l1 to carrying reel I8.The insulated conducting cable I6 is shown connected at its lower end tcthe fluid level measuring device 6. An electric circuit is employed inconnection with the measuring device S, for the purpose of indicatingthe level of the conducting liquid in the well bore, and consists of asource of electric current, such as battery I9, one pole of which isshown connected to tubing 5 by clamping means 20. The other pole of thebattery I9 communicates with the reel shaft 2|, which in turn is inelectrical contact with cable I6. Disposed in the circuit is anelectrical current measuring device 22, such as an ammeter suitable toindicate the current that may flow through the circuit. In the moredetailed view of the uid level measuring device shown in Figure 2, aconventional iron collar or coupling 23 engages the lower end of thetubing 5, and a tapered seat member 2li. Attached to the seat member 24in screw threaded engagement therewith is a packing gland 25, throughwhich the cylindrical tubular member 26 can be slidably moved in asealing relationship. The tubular member 26, formed of metal or otherelectrically conducting material is shown enlarged at the upper portionto form a tapered seating portion 21, which conforms to the innersurface of seat member 24, thus producing a seal when the surfaces aremaintained in a contacting relationship. The seat member 24 also servesas a stop, preventing the measuring device from being lowered out of thetubing. Entry ports 28 and exit ports 29 are provided at the upper andlower ends, respectively, of the tubular member 26, and serve as a meanswhereby liquid can enter the well bore from tubing 5.

An electrode 30, which may suitably be a cylindrical band made of copperor other suitable conducting metal, is shown mounted on the outersurface of tubular member 26 a short distance above the fluid exit ports29, and is electrically insulated from the tubular member by aninsulating shell 3I made of Bakelite, hard rubber, or the like.Insulated conducting cable I6, carried by reel I8, extends into the welland is attached to the tubular member 26 with a suitable clamp 32, andserves as a means whereby the measuring device can be raised and loweredin the well. The cable I6 continues through the clamping means 32 and isconnected through an insulated bushing 33 with electrode 30. Springfingers 34 depend from packing gland and engage the tubular member 26 inelectrical contacting relationship as it is slidably moved through thepacking gland.

In the modification shown in Figures 3 and 4 a cable 35 having twoconductors 36 and 31 separated from each other by electrical insulation38 as shown in Figure 4 has been substituted for the cable I6 having thesingle conductor shown in Figures 1 and 2. One of the conductors ofcable 35 may consist of an outer layer of woven steel wire 36 whichserves to support the level measuring device as it is being lowered intothe Well. The cable 35 is attached to tubular element 26 by clampingmeans 39. The outer con-- ductor 36 is grounded to the clamping means 39and may be secured thereto as by soldering, brazing, or the like. Theinsulated inner conductor extends through the tubular element and iselectrically connected to electrode 30, being electrically insulatedfrom tubular element 26 by bushing 33. With the arrangement of Figures 3and 4 the spring fingers 34 shown in Figure 2 may be eliminated sincethe well tubing is not used to complete the circuit. Instead, thecurrent travels down the outer conductor and through the tubular element26 and is completed by conducting iiuid 1 through electrode 30 andconductor 31. At the top of the well the cable 35 is carried by reel I8which is provided with suitable means for electrically connecting thecable conductors with measuring instrument 22 and battery I9. Such meansmay consist of a suitable shaft support 40 making contact with the reelshaft which is in turn contacted by one of the cable conductors. Theother conductor contacts ring 4I insulated from the reel I8 byinsulation 42. A brush 43 is provided to maintain electrical contactwith ring 4I while electrical lead 44 connects the battery I9 to thebrush 43.

In employing the method of the invention illustrated by Figures 1 and 2in carrying out an acid treatment, for example, the assembled meassuringdevice is positioned in the well bore so that as the fluid levelmeasuring device 6 is raised and lowered the electrode`30 will belocated in the vicinity of the upper level of the productive stratum 4,which is to be subjected to the action of the acid. The well is thenpreferably filled With oil to render it hydrostatically controllable,

by pumping the oil into the well through pipe I3, while the valve I I inpipe I0 is maintained in an open position. After the well has beenfilled with oil, the introduction of acid into the well through pipe I3in communication with the tubing 5 is started, while oil is allowed toescape at the casing head through pipe I0. When the acid reaches thebottom of the well and rises in the well bore to a point where it makescontact with electrode 30, electric current willf flow through thecircuit completed between the well tubing and the electrode 30 by theacid solution 1. The fiow of current through the circuit will beindicated on the current indicating device 22, in this case an ammeter.Valve Il is then closed and pressure is applied to force the acidsolution into the formation. By raising and lowering the measuringdevice as the introduction of the acid is continued and observing thelevel at which current ceases to flow through the electrical circuit,knowledge of the level at which the acid is entering the formation isavailable at any time during the treatment. If at any time during thetreatment, the acid rises above the level at which its entry into theformation is desired, indicating that oil is escaping into theformation, additional oil may be pumped into the well through pipe I9communicating with the casing, so as to control the level of the acid atany desired point. Also, if the acid level, as indicated by themeasuring device, falls below the desired level indicating that the acidis draining away into the formation adjacent the lower portion of thewell bore, a quantity of blanketing medium, such as a solution of anorganic jellifying material described in U. S. Patent No. 1,998,756, maybe introduced into the bottom of the well to prevent such drainage.

Although it is usually preferable to carry out a treatment in the mannerjust described, wherein the measuring device is raised and loweredduring the course of the treatment in order to ascertain the level ofthe acid at all times, in some instances, it may be merely desirable tokeep the level of the acid from rising above a certain point in the wellbore. In this case the means provided for maintaining a sealingrelationship between the well tubing and fluid level measuring device asit is raised and lowered may be dispensed with and the measuring deviceallowed to rest on the sealing seat member in a fixed position.

Instead of connecting one electrical lead to the tubing string tocomplete the circuit as described above, other means of completing thepath of the current may be provided. For example, the earth or rocksurrounding the well bore may be made to act as an electrical conductorand the current caused to pass through the earth between a suitableground connection such as shown at 45 Figure 1, and the conductingliquid in the well bore, in place of the connection to the tubing 5 bythe clamping means 2li. f

The operation of the method and apparatus employing the structure ofFigures 3 and 4 is similar to that described in connection with Figures1 and 2. In this instance, however, the tubing does not serve as aconductor to complete the electrical circuit and, therefore, it isunnecessary for the tubular element 26 to maintain electrical contactwith the well tubing. As the level of the conducting liquid 1 rises inthe bore and contacts the electrode 30 the electric circuit is completedbetween the outer cable conductor pr. s,

36, tubular element 26, conducting liquid l, electrode 30, and cableconductor 31.

It is, of course, evident that two separate and suitably insulatedconducting cables may be employed instead of the single cable or thecable and the well tubing to complete the electric circuit.

Although the apparatus has been described with particular reference toits use in connection with an acid treatment of a well, it is to beunderstood that it may be suitably used in treating a well wherein anyelectrically conductive liquid is employed. It will also be apparentthat the device may be used to ascertain the lower level of an acid orother conducting fluid in those instances wherein a non-conductingblanketing medium such as is disclosed in U. S. Patent 1,998,756 isemployed.

In the foregoing manner, the treatment of a well with an acid reagent orother electrically conductive liquid may be carried out much moreeffectively, since the point of entry of fluid into the formation can beaccurately dermined and controlled at any time during the treatment.

This application is a continuation-impart of my co-pending applicationSerial No. 265,753, led April 3, 1939 and not forfeited.

Other modes of applying the principle of my invention may be employedinstead of those explained, change being made as regards the meansherein disclosed, provided those stated by any of the following claimsor their equivalent be employed.

I therefore particularly point out and distinctly claim as my invention:

1, In apparatus for introducing into a well an electrically conductingliquid and measuring its level therein, the combination of a tubingstring, a, tubular member removably engaging the lower end of the tubingstring and provided with openings permitting the passage of liquidthrough it into the well, an electrode mounted on the tubular memberbetween its ends and insulated therefrom, an insulated conductorthreaded through the tubing string and connected to the electrode, anelectrical circuit including the conductor and means for detectingcurrent flow when an electricallyconducting liquid in the well makescontact with the electrode.

2. In a fluid level indicating device for wells the combination of atubing string, a tubular member adapted to pass through the tubingstring, said tubular member being provided with openings to allow flowof fluid from the tubing string therethrough into the well bore, meanscarried by the lower end of the tubing string adapted to engage thetubular member in sealing relationship, an electrode mounted on theouter surface of the tubular member and electrically insulatedtherefrom, an electrical circuit including a single cable having twoconductors insulated from each other one of said conductors beinggrounded to the tubular member and the other conductor being connectedto the electrode, and means to indicate flow of current when aconducting liquid makes contact between the electrode and the tubularmember.

3. In apparatus for introducing into a well an electrically conductingliquid and measuring its level therein, the combination of a tubingstring having a seating member at its lower end, an electrode carryingmember adapted to pass through the seating member in uid tight tele-D831' Cn VN scopic enga-gement therein provided with openings for thepassage of liquid through it into the well, an electrode mounted on theoutside of the electrode carrying member intermediate its ends andinsulated therefrom, an insulated conductor threaded through the tubingstring and connected to the electrode, an electrical circuit includingthe conductor and means for detecting current flow when an electricallyconducting liquid in the well makes contact with the electrode.

4. In apparatus for introducing into a well an electrically conductingliquid and measuring its level therein, the combination of a tubingstring having a seating member at its lower end, an electrode carryingmember adapted to pass through the seating member in telescopicengagement therewith provided with openings for the passage of liquidthrough it into the well, an electrode mounted on the outside of theelectrode carrying member intermediate its ends and insulated therefrom,a cable attached to the electrode carrying member adapted to lower orraise the same through the tubing string, said cable including anelectrically insulated conductor connected to the electrode, anelectrical circuit including the conductor and means for detectingcurrent flow when an electrically conducting liquid in the well makescontact with the electrode.

5. In apparatus for introducing into a well an electrically conductingliquid and measuring its 1evel therein, the combination of a tubingstring having a seating member at its lower end, an electrode carryingmember having a head portion adapted to engage the seating member and atubular portion adapted to pass through the seating member in telescopicengagement therewith provided with openings near its lower end for thepassage of liquid through it into the well, an electrode'mounted on theoutside of the tubular portion of the electrode carrying memberintermediate its end and insulated therefrom, an insulated conductorthreaded through the tubing string and connected to the electrode, anelectrical circuit including the conductor and means for detectingcurrent flow when an electrically conducting liquid in the well makescontact with the electrode.

6. In apparatus for introducing into a well an electrically conductingliquid and measuring its level therein, the combination of a tubingstring having a seating member at its lower end, an electro-de carryingmember having a head portion adapted to engage the seating member and atubular portion adapted to pass through the seating member in fluidtight telescopic engagement therewith provided with openings near itslower end for the passage of liquid through it into the well, anelectrode mounted on the 'outside of the tubular portion of theelectrode carrying member intermediate its ends and insulated therefrom,a supporting cable attached to the electrode carrying member adapted tolower or raise the same through the tubing string, said cable includingan insulated conductor connected to the electrode, an electrical circuitincluding the electrode a source of current and a current indicatorconnected to the conductor for detecting current flow when anelectrically conducting liquid in the well makes contact with theelectrode.

ORMOND E. BARSTOW.

